Immunoglobulins or antibodies in their native form are usually tetrameric glycoproteins composed of two light and two heavy chains. Antibodies contain constant domains which assign the antibodies to different classes like IgA, IgD, IgE, IgM, and IgG, and several subclasses like IgG1, IgG2, IgG3, and IgG4. Antibodies of humans of class IgG1 and IgG3 usually mediate ADCC (antibody-dependent cell-mediated cytotoxicity).
There are also known other molecules which are antibody-like and contain, for example, a binding domain of a heterologous protein such as a receptor, ligand or enzyme, and the Fc region of an antibody. Such Fc fusion proteins are described, for example, by Stabila, P., et al., Nature Biotech 16 (1998) 1357-1360 and U.S. Pat. No. 5,610,297.
Monoclonal antibodies elicit four effector functions: ADCC, phagocytosis, complement-dependent cytotoxicity (CDC) and half-life/clearance rate. ADCC and phagocytosis are mediated through the interaction of cell-bound antibodies with FcγR (Fc gamma receptors); CDC through the interaction of cell-bound antibodies with a series of proteins that constitute the complement system. CDC is related to C1q binding C3 activation and/or Fc receptor binding of the Fc part. If C1q binding C3 activation and/or Fc receptor binding of an antibody constant part should be reduced, usually IgG4 antibodies are used which do not activate the complement system, do not bind C1q and do not activate C3. Alternatively, Fc parts comprising a gamma-1 heavy chain constant region with certain mutations such as L234A and L235A or D265A and N297A (WO 99/51642) are used.
It is well-known in the state of the art to modify the constant domains of antibodies for improving effector functions. Such methods are described, for example, in WO 99/54342.
Routier, F. H. et al., Glycoconjugate J. 14 (1997) 201-207 report the glycosylation pattern of a humanized IgG1 antibody expressed in CHO-DUKX cells. This antibody shows a molar ratio of Fuc:Man of 0.8:3.0, which refers to a fucosylation ratio of 80%. Niwa, R. et al., J. Immunol. Methods 306 (2005) 151-160 report for anti-CD20 IgG1 and IgG3 antibodies recombinantly produced in CHO DG44 fucosylation of 90% resp. 91%. Mimura, Y et al., J. Immunol. Methods 247 (2001) 205-216 report that butyrate increases production of human chimeric IgG in CHO-K1 cells whilst maintaining function and glycoform profile. The oligosaccharide profiles show a considerable content of afucosylated glycan structures. Raju, T. S., BioProcess International 1 (2003) 44-53 report the impact of glycosylation variation by expression systems on the biological activity of therapeutic immunoglobulins and the nomenclature. Ma, S., Anal. Chem. 71 (1999) 5185-5192 report the carbohydrate analysis of rituximab. Rituximab shows 9-10% fucosylation (Niwa, R. et al., J. Immunol. Methods 306 (2005) 151-160). Fujii, S., J. Biol. Chem. 265 (1990) 6009-6018 report that bovine IgG includes about 11% afucosylated IgG. Mizouchi, T., J. Immunol. 129 (1982) 2016-2020 report that human IgG is about 14% afucosylated. Bergwerff, A. A., Glycoconjugate J. 12 (1995) 318-330 report that antibodies produced in mouse SP2/0 contains N-glycolylneuraminic acid (NGNA) oligosaccharides in large amounts. Nahrgang, S. et al., In: Animal Cell Technology: Products from Cells, Cells as Products, Bernard, A. et al. (eds.), Kluwer Academic Publishers, Dordrecht, N L, 1999, pp. 259-261, report that for CHO expression of IgG1 after transient transfection a poor overall glycosylation is found. Lund, J. et al., Mol. Immunol. 30 (1993) 741-748 report recombinant production of a mouse-human chimeric antibody in mouse transfectoma cells. The IgG1 antibody is afucosylated in an amount of 13%. Patel, T. P. et al., Biochem. J. 285 (1992) 839-845 report on glycosylation of antibodies from hybridoma cells and mouse ascites. Niwa, R. et al., J. Immunol. Methods 306 (2005) 151-160, report for CD20 IgG1 antibody a fucosylation of 91% after recombinant production in CHO DG44 and Mori, K. et al., Biotech. Bioeng. 88 (2004) 901-908, a fucosylation of 94%. Davies, J., et al., Biotechnol. Bioeng. 74 (2001) 288-294 report that expression of antibodies with altered glycoforms leads to an increase of ADCC. Sheeley, D. M., et al., Anal. Biochem. 247 (1997) 102-110 compare antibody glycosylation in different expression systems. Shields, R. L., et al., J. Biol. Chem. 277 (2002) 26733-26740 report that lack of fucose on human IgG1 Fc improves FcγRIII binding and ADCC. Zhu, L., et al., Nature Biotechnol. 23 (2005) 1159-1169 report on the production of human antibodies in chicken eggs. WO 2004/087756 and WO 2005/005635 disclose improved antibodies against IGF-1R.